The autoclave cure process is the representative composite fabrication technique for high quality composite materials for the aerospace and defense industry application. After lay up and vacuum-bagging in a complicated sequence, the several composite materials needed in autoclave curing, are cured under controlled temperature and pressure. The autoclave curing, in which the total cure process requires at least 4-6 hours, is a very expensive process. Therefore, the determination of an optimal cure process for composite prepregs is very important for guaranteed quality as well as being important economically.
The cure kinetics of resin and the compaction behavior of a prepreg should be examined in order to optimize the cure cycle of the prepreg. The measurement of resin cure kinetics is so far carried out by DSC (Differential Scanning Calorimeter) and general thermal analyzing systems.
However, there have been no continuous monitoring methods available for the observation of the compaction behavior of a prepreg in an autoclave.
The theoretical model of resin flow and compaction behavior of the prepreg in curing has been proposed by G. S. Springer (J. of Composite Materials, 1983, Vol. 17) and T. G. Gutosky (SAMPE Quarterly, Vol. 16).
However, these theoretical models cannot be proven because of the lack of experimental methods. The experimenter must run many batches of autoclave curing using trial and error at the different curing temperatures and pressures to obtain a sufficient amount of data which can experimentally determine the optimal cure process. If the compaction behavior of a prepreg in autoclave curing can be continuously monitored, it would be contributed to the effective determination for the optimal condition of an autoclave curing process. This measuring system, which can determine the condition of an optimal cure process, is an excellent device to obtain the degree of curing and variation in thickness of a prrpreg which is optimal in physical and mechanical properties.